This invention relates to a new and improved concrete armor shape for use in the design and construction of breakwaters, flood control structures, armored revetments, jetties and for the rapid building of off-shore islands. Since the early 1950's concrete armor shapes have been developed and have been used throughout the world with varying degrees of success. However, recently several major breakwaters have failed due to the lack of structural integrity of some of the armor units utilized in the building of the breakwaters. The present invention is of rugged design and provides special operational attributes not found in other concrete armor shapes.
The building of a major breakwater is an extremely costly venture that usually takes years to design and build. When erected in deep water areas, which can generate large waves, the breakwater is generally armored with large concrete armor units because of their superior stability factor over stone when subjected to severe wave attack. One of the major drawbacks in the use of concrete armor shapes for protection of marine structures is the high cost of producing the units which are usually cast only once every 24 hours. Therefore it is easy to understand that for a given structure requiring thousands of units, the casting operation can take months and even years to complete a given project. Therefore it is evident that it is desirable that any shape proposed should preferably be simple to cast at a rapid rate.
The construction element includes a trapezoidal inner core supported by trapezoidal legs which space the inner core apart from any surface on which it rests, regardless of which face of the unit is disposed downward. The overall shape of the unit of the present invention is generally trapezoidal with specifically designed and shaped void segments cut into every plane surface for the release of water pressure to prevent uplift pressures from moving the units out of position. The void segments on each surface of the units also form legs for setting the units and also provides for a void area beneath the blocks for release of hydrostatic head pressure. The leg configuration also permits ease of installation on a rough stone surface. No matter how the units are arranged (patterned or random) the void zones permit escape of water pressure which is of prime importance for stability. When the units are placed pell-mell they form a highly stable mass permitting the release of water pressure in every direction even if one block is placed directly on top of another unit. When the units are set in a pattern, either laying down or standing erect, they form a stable mass and as the wave energy moves up an array of the blocks it will collide with the water jets that pass through the void area in each unit. An important aspect of the invention is the creation of high frictional contact between the units while still maintaining a channel for release of water pressure.
Of major importance in this invention is the structural integrity of the unit itself which is the prime factor in the erection of marine structures. Serious breakage problems have recently occurred on certain of the prior concrete armor shapes because of the lack of structural integrity of the units when they are subjected to eccentric movement and consolidation on a breakwater slope. In the present invention the breaking of the legs will not effect the structural integrity of the basic core of the element.
Another important object of the invention is to provide an armor shape capable of being produced with a one-piece mold.
Another object of the invention is the high degree of porosity, which exceeds 50%, even when the units are randomly placed and regardless of what position the blocks find, there is always a positive outlet for release of water pressure.
Another object of the invention is to provide lugs on the top and bottom segments of the unit for placement of the units on uneven stone surfaces with the lugs on the top of the block providing energy dissipation as water flows over the surface.